Isaac Asimov is rightfully considered a giant in the world of science fiction. His vast collected works (he has been published in 9 of the 10 Dewey Decimal categories) included pioneering work in robotics (a term, like "positronic", that he invented). Without Asimov, there may never have been a Data, or an Ultron. That said, my favorite Asimov character, and one my favorite in all of science fiction, is his human detective, Elijah Baley.
I'm not partial to the Foundation series. For me, the Robot series is far more intimate and engaging. Baley is a policeman on the Earth of 3,000 in the future, and he is the mortal lens through which we explore a world populated with robots, most importantly his mechanical partner, R. Daneel Olivaw. Baley is moody and restless, a very human character we readily recognize despite the temporal gap. His relationship with Olivaw, which grows into a profound mutual respect and friendship, presages the Kirk-Spock dynamic, among others. Thrust into a wider universe and forced to confront the explosive changes coming to a very staid society, Baley proves a reluctantly resourceful hero. As with much of Asimov's work, the speculative aspects are merely setting; he is a keen observer of the human condition and a master storyteller. As Baley would say, "Jehosaphat!"